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michelgutman
michel ... 7/26/2013
2002 Jeep Liberty Limited 6Cyl3.7L - Engine
Whenever my 2002 Jeep Liberty Limited is not in motion for a prolonged amount of time (sitting in traffic), it overheats
At the same time, the air conditioning blows warm air.....
5 Answers
  • wbrockstar
    wbrockstar 7/26/2013
    Sounds like the cooling fan is malfunctioning.When vehicle is moving,airflow from front of car cools down the coolant in radiator and blows across the ac condenser which is the part that looks like a small radiator that also mounts in front of the radiator.When you are at a stand still,the coolant in radiator and the freon inside inside of the condenser can only cool down if the cooling fans are working properly.Check fuses,relays,fan motor,and cooling fan switch for proper function,then replace at fault components
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    wbrockstar
    michelgutman 7/27/2013
    Happened again... when the temp got really high (almost in the red), the fan kicked in for around 5 seconds.... then shut off again..... How can I test the relay?
  • wbrockstar
    wbrockstar 7/27/2013
    Actually,there are normally other relays close by that should have the same number on them.Remove one of those and put it in place of the relay you suspect is faulty.As long as whatever relay you remove isnt controlling a system on the car that you cant do without,just long enough for testing purposes
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    wbrockstar
    wbrockstar 7/27/2013
    Also,see if cooling fans run only while the ac is running.If so,thats normally a dead giveaway for bad cooling fan switch
    wbrockstar
    michelgutman 7/27/2013
    The cooling fan never runs... It only started running when it nearly totally overheated... and the AC works fine, as long as the vehicle is in motion....
  • John's Auto Repair
    John's Auto Repair 7/27/2013
    Sounds like the High Pressure Switch in the A/C high side line may not be working. It usually
    turns the fan on when High Side Pressure reaches around 225 to 250 PSI.
    Reply
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    John's Auto Repair
    michelgutman 7/28/2013
    Would that cause overheating when the car isn't in motion?
  • wbrockstar
    wbrockstar 7/29/2013
    Normally when youre in motion the air in front of the car blows through the ac condenser ( thats mounted in front of the radiator ) and through the fins on the radiator.Thats how the coolant in the radiator gets cooled down,when in motion.When youre at a stand still,the radiator and condenser rely totally on the cooling fans in order to keep the coolant in radiator cooled down,so when engine reaches operating temp again,the thermostat opens and the hot coolant in engine and cool coolant in radiator swap places until the cycle begins the next time around.The fans should be coming on somewhere between 200-230 degrees.It doesnt take but a few really bad overheating in the redzone sessions before youll be removing the heads because they warped or you blew head gasket.
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  • wbrockstar
    wbrockstar 7/29/2013
    If the ac pressure switch was faulty,the ac wouldnt be working at all.If freon gets too low in system,this sensor tells the compresser to not function,so that the compresser wont burn up.Earlier posts I said ac condenser,but I meant to say ac evaporater core,sorry.DO THIS::check and see if youve got a sensor screwed into the lower (engine )side of radiator.If so,unplug harness and take a short piece of jumper wire and jump it across two terminals on harness.Start jeep and see if cooling fans are now running.If so,replace that switch and after you get done replacing,make sure you wait until jeep gets up to 200 degrees before checking again to make sure fans run.They wont run until that temp is reached,unless ac is on.Another thing,ac will blow warm if engine is overheating because computer shuts compresser down to reduce engine load and damage
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